In recent years, a flash apparatus has been widely employed in various kinds of optical apparatus which requires light of flash. Particularly, in the art of photography, artificial light is used to illuminate an object to be photographed. One form of artificial light which into wide use is so-called a flash tube. In such devices, a flash tube is provided in order to illuminate an object to be photographed.
It is common practice in electric flash devices to obtain high intensity illumination for photographic purposes by discharging a charged capacitor through a gas-filled flash tube. A low voltage D.C. power source is generally employed together with suitable circuitry in order to obtain the relatively high D.C. voltage which is needed to charge the flash capacitor to a value for each firing of the flash tube. Since an electric flash device of this type is generally portable, batteries are usually employed as the source of low D.C. voltage. High D.C. voltage is obtained from the batteries through the use of a voltage convertor. A convertor includes a transformer for charging the low alternating voltage to high A.C. voltage, and a rectifier for converting the high A.C. voltage which is applied to the flash capacitor in order to charge it.
It can readily be understood that under ordinary circumstances when an electric flash device is being used, a substantial portion of the time during which the device is turned on may be standby time; that is, elapsed time after power supply has charged the capacitor to a suitable value and before the camera shutter is tripped discharging the capacitor through the flash tube. During this time the power supply consumes energy from the batteries without producing any useful results. The energy loss may be significant, particularly when the device includes transformers. As the batteries age their output voltage drops and a longer period of time is required for firing the flash tube. In addition, as the output voltage of the batteries decreases with age, the device becomes incapable to use for flashing the flash tube.